1. Field of the Invention
The invention relates to a semiconductor device, more particularly to a method for forming an electrical contact of a semiconductor device.
2. Description of the Related Art
Referring to FIGS. 1 and 2, a conventional semiconductor device 1 is shown to have a lower metal layer 10, a lower dielectric layer 11 on top of the lower metal layer 10, an upper metal layer 12 on top of the lower dielectric layer 11, and an upper dielectric layer 13 on top of the upper metal layer 12. The semiconductor device 1 further has a contact region 14 in the form of a cavity that extends through the upper dielectric layer 13, the upper metal layer 12 and the lower dielectric layer 11 for access to a solder pad portion 16 of the lower metal layer 10. A grounding trace 17 is disposed on the upper dielectric layer 13 and surrounds the contact region 14 to protect the semiconductor device 1 from static electricity. To enable electrical connection of the lower metal layer 10 with an external circuit (not shown), a contact body 15, which is made of solid metal, is mounted in the contact cavity 14 via conventional wire-bonding techniques. It is noted that, if liquid metal is used to form the contact body 15, short-circuiting will occur due to formation of an undesired connection between the lower and upper metal layers 10, 12.
It is desirable to provide an alternative contact-forming method for a semiconductor device so that manufacturing costs can be lowered in order to enhance market competitiveness.
Therefore, the main object of the present invention is to provide a semiconductor device and a method for forming an electrical contact of the semiconductor device at a relatively low cost.
According to one aspect of the invention, a semiconductor device comprises: a lower metal layer; a lower dielectric layer on top of the lower metal layer; an upper metal layer on top of the lower dielectric layer; an upper dielectric layer on top of the upper metal layer; a contact region formed as a cavity that extends through the upper dielectric layer, the upper metal layer and the lower dielectric layer for access to a solder pad portion of the lower metal layer; a dielectric lining layer that lines a peripheral cavity-confining surface of the cavity and that is transverse to a plane of the lower metal layer to isolate the upper metal layer from the lower metal layer while permitting access to the solder pad portion of the lower metal layer; and an electrical contact that fills the cavity and that enables external electrical connection with the lower metal layer.
According to another aspect of the invention, there is provided a contact-forming method for a semiconductor device having a lower metal layer, a lower dielectric layer on top of the lower metal layer, an upper metal layer on top of the lower dielectric layer, an upper dielectric layer on top of the upper metal layer, and a contact region formed as a cavity that extends through the upper dielectric layer, the upper metal layer and the lower dielectric layer for access to a solder pad portion of the lower metal layer. The contact-forming method comprises:
forming the semiconductor device with a dielectric lining layer that lines a peripheral cavity-confining surface of the cavity and that is transverse to a plane of the lower metal layer to isolate the upper metal layer from the lower metal layer while permitting access to the solder pad portion of the lower metal layer; and
filling the cavity with a liquid metal to form an electrical contact that enables external electrical connection with the lower metal layer.